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Mendocino County, CA Accessory Structures: ADU Owner Occupancy (2026)

Some Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

Key Facts

Who must reside on-site
Owner of the lot
Exempt owners
Government agency, land trust, housing org
Prerequisite for permit
Recorded deed restriction
Applies to
Junior ADUs only
Governing section
Sec. 20.166.030(C)(8)(a),(c)

Summary

Building a junior accessory dwelling unit in unincorporated Mendocino County requires the lot owner to live on-site, unless the owner is a government agency, land trust, or housing organization, and a recorded deed restriction locking in that requirement before any permit issues.

These county ordinances apply to unincorporated areas of Mendocino County. Incorporated cities within the county may have their own rules that take precedence over county-level regulations.

(8)Owner Occupancy Requirements for Junior ADUs.(a)The owner of the lot must reside on-site. Owner-occupancy shall not be required if the owner is another governmental agency, land trust, or housing organization.(c)Prior to obtaining a building permit for a Junior Accessory Dwelling Unit, a deed restriction, approved by the County, shall be recorded with the County Recorder's office, which shall include the pertinent restrictions and limitations of a junior accessory dwelling unit, which shall run with the land, and be binding upon any future owners, heirs, or assigns.

View official code

Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 75).

Full Breakdown

Sec. 030(C)(8) sets owner-occupancy requirements specifically for junior ADUs, a category limited to 500 square feet built within an existing single-unit home's footprint under Sec. 020(C). Subsection (a) requires the owner of the lot to reside on-site, whether in the primary residence or the JADU itself; the only carve-out is when the owner is a governmental agency, land trust, or housing organization rather than an individual. Subsection (c) requires that before a building permit issues for the JADU, the owner record a deed restriction approved by the County with the County Recorder's office.

That restriction must spell out the JADU's occupancy and other limitations, runs with the land, and binds every future owner, heir, or assign, so a buyer who purchases the parcel later inherits the same owner-occupancy obligation. This owner-occupancy requirement applies to JADUs only; the standard attached and detached ADU categories described in Sec. 030(A) and (B) carry no comparable owner-occupancy condition, reflecting the more flexible standards state ADU law applies to full-size units versus the smaller, in-home JADU category.

Violations & Fines

Occupying or renting a JADU without the owner residing on the parcel, or without the recorded deed restriction on file, is a violation of Chapter 20.166's development standards and is enforced under Sec. 20.216.010: prosecutable as an infraction under Government Code Section 25132 or handled administratively under Chapter 1.08, with the Planning and Building Services Department authorized to issue a stop-work order and record a notice of violation and lien against the property.

Frequently Asked Questions

Must the property owner live on-site to build a junior ADU in Mendocino County?
Yes. Sec. 20.166.030(C)(8)(a) requires the owner of the lot to reside on-site, unless the owner is a governmental agency, land trust, or housing organization rather than an individual owner.
What has to be recorded before I get a JADU building permit?
A deed restriction approved by the County, recorded with the County Recorder's office per Sec. 20.166.030(C)(8)(c). It spells out the JADU's restrictions, runs with the land, and binds future owners and heirs.
Does a full-size detached ADU require owner-occupancy in Mendocino County?
No. The owner-occupancy requirement in Sec. 20.166.030(C)(8) applies only to junior accessory dwelling units; standard attached and detached ADUs under Sec. 20.166.030(A) and (B) carry no such condition.

Sources & Official References

Other rules in Mendocino County

All Mendocino County rules

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